Oncornavirus genome RNA will be subjected to nucleotide sequence-analysis in order to determine if the subunits which comprise the high molecular RNA molecular are heterogeneous, and likely, theregore, to contain the same genetic information. Regions of the RNA preceeding the polyriboadenylic acid (poly (A)) tracts as well as regions of the RNA encompassing the 5'-chain termini will be characterized. Nucleotide sequences preceding the poly (A) tracts in the subunit RNA molecules are also of interest because they are likely to constitute, at least in part, 'recognition' sites for the poly (A) synthetases. The nature of the 'linkage' responsible for maintaining the association of the RNA subunits with the low molecular weight (lesser than 10S) RNA chains will be studied by isolating and characterizing double-stranded RNA fragments originating from interchain complimentary base-paired regions. To gain some insight into the 'message' function of reovirus mRNA, nucleotide sequence-analysis will be carried out on the untranslated regions. These studies will demonstrate to what extend the frequency of translation regions. These studies will demonstrate to what extent the frequency of translation and transcription are mediated by nucleotide sequence and/or secondary structure in the RNA. Double-stranded reovirus RNA will be transcribed in vitro in the presence of P32 nucleoside triphosphates of high specific activity. For studies on the chain termini, synchronized systems will be employed to 'pulse-label' short in ribosime binding studies in order to isolate and characterize the initiation regions of the RNA. Correlative studies will be carried out on animal cell mRNAs so that these can be compared with viral RNAs translated in the same cell. In these studies ribosome binding sites and untranslated regions of the RNA will be examined.